Telecommunications apparatus and methods

ABSTRACT

A method is for use in a mobile telecommunications network that comprises a base station providing wireless connectivity within a base station cell, a mobile node providing wireless connectivity within a local cell and configured to communicate wirelessly with the base station, and a terminal configured to communicate wirelessly with the base station and configured to communicate wirelessly with the mobile node; and the method comprises: activating a limited local radio connection between the terminal and the mobile node; starting a first timer of fixed duration when or after the limited local radio connection is activated; and when the first timer has expired, activating a limited base station radio connection between the terminal and the base station and terminating the limited local radio connection between the terminal and the mobile node.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.16/724,305, filed Dec. 22, 2019, which is a continuation of U.S.application Ser. No. 15/781,492, filed Jun. 5, 2018 (now U.S. Pat. No.10,524,306), which is based on PCT filing PCT/EP2016/080696, filed Dec.12, 2016, which claims priority to EP 15201658.0, filed Dec. 21, 2015,the entire contents of each are incorporated herein by reference.

BACKGROUND Field

The present disclosure relates to telecommunications apparatus andmethods.

Description of Related Art

The “background” description provided herein is for the purpose ofgenerally presenting the context of the disclosure. Work of thepresently named inventors, to the extent it is described in thisbackground section, as well as aspects of the description which may nototherwise qualify as prior art at the time of filing, are neitherexpressly or impliedly admitted as prior art against the presentinvention.

Mobile telecommunication systems, such as those based on the 3GPPdefined UMTS and Long Term Evolution (LTE) and Long Term EvolutionAdvanced (LTE-A) architecture, are able to support more sophisticatedservices than simple voice and messaging services offered by previousgenerations of mobile telecommunication systems. For example, with theimproved radio interface and enhanced data rates provided by LTEsystems, users can enjoy high data rate applications such as videostreaming and video conferencing on mobile communications devices thatwould previously only have been available via a fixed line dataconnection.

The demand to deploy fourth generation networks is therefore strong andthe coverage area of these networks, i.e. geographic locations whereaccess to the networks is possible, is expected to increase rapidly.However, although the coverage and capacity of fourth generationnetworks is expected to significantly exceed those of previousgenerations of communications networks, there are still limitations onnetwork capacity and the geographical areas that can be served by suchnetworks. These limitations may be particularly relevant in situationsin which there is a desire for a group of terminal devices(communications devices) to exchange information with each other in afast and reliable manner. To help address these limitations approacheshave been proposed in which terminal devices within a wirelesstelecommunications system may be configured to communicate data directlywith one another without some or all their communications passingthrough an infrastructure equipment element, such as a base station.Such communications are commonly referred to generally as adevice-to-device (D2D) communications. Many device-to-devicecommunications may be transmitted by one device to a plurality of otherdevices in a broadcast like manner and so in that sense the phrase“device-to-device communications” also covers “device-to-devicescommunications”.

Thus, D2D communications allow communications devices that are insufficiently close proximity to directly communicate with each other,both when within the coverage area of a network and when outside anetwork's coverage area (e.g. due to geographic restrictions on anetwork's extent or because the network has failed or is in effectunavailable to a terminal device because the network is overloaded). D2Dcommunications can allow user data to be more efficiently and quicklycommunicated between communications devices by obviating the need foruser data to be relayed by a network entity such as a base station. D2Dcommunications also allow communications devices to communicate with oneanother even when one or both devices may not be within the reliablecoverage area of a network. The ability for communications devices tooperate both inside and outside of coverage areas makes wirelesstelecommunications systems that incorporate D2D capabilities well suitedto applications such as public protection/safety and disaster relief(PPDR), for example. PPDR related communications may benefit from a highdegree of robustness whereby devices can continue to communicate withone another in congested networks and when outside a coverage area. 3GPPhas developed some proposals for such public safety D2D use in LTEnetworks in Release12.

In parallel, the development of relay nodes and other local cellarrangements in telecommunications systems is expected to facilitatecommunications with base stations and potentially to expand the range ofcoverage of the base stations by relaying communications betweenterminal devices and base stations.

There is a need to provide appropriate resource allocation andmanagement in local cell and D2D communication arrangements.

SUMMARY

The present disclosure can help address or mitigate at least some of theissues discussed above.

According to a first example aspect there is provided a method for usein a mobile telecommunications network, the mobile telecommunicationsnetwork comprising a base station providing wireless connectivity withina base station cell, a mobile node providing wireless connectivitywithin a local cell and configured to communicate wirelessly with thebase station, and a terminal configured to communicate wirelessly withthe base station and configured to communicate wirelessly with themobile node; the method comprising: activating a limited local radioconnection between the terminal and the mobile node; starting a firsttimer of fixed duration when or after the limited local radio connectionis activated; and when the timer has expired, activating a limited basestation radio connection between the terminal and the base station andterminating the limited local radio connection between the terminal andthe mobile node.

According to a second example aspect there is provided a mobiletelecommunications network, the mobile telecommunications networkcomprising a base station providing wireless connectivity within a basestation cell, a mobile node providing wireless connectivity within alocal cell and configured to communicate wirelessly with the basestation, and a terminal configured to communicate wirelessly with thebase station and configured to communicate wirelessly with the mobilenode, wherein the mobile telecommunications network is configured to:activate a limited local radio connection between the terminal and themobile node; start a first timer of fixed duration when or after thelimited local radio connection is activated; and when the timer hasexpired, activate a limited base station radio connection between theterminal and the base station and terminate the limited local radioconnection between the terminal and the mobile node.

According to a third example aspect there is provided a mobiletelecommunications network, the mobile telecommunications networkcomprising a base station providing wireless connectivity within a basestation cell, a mobile node providing wireless connectivity within alocal cell and configured to communicate wirelessly with the basestation, and a terminal configured to communicate wirelessly with thebase station and configured to communicate wirelessly with the mobilenode, wherein the mobile telecommunications network is configured tocarry out the method of the first aspect and/or any of its variationswithin the scope of the claims.

According to a fourth example aspect there is provided a method ofoperating a terminal for use in a mobile telecommunications networkcomprising a base station providing wireless connectivity within a basestation cell, and a mobile node providing wireless connectivity within alocal cell and configured to communicate wirelessly with the basestation, wherein the terminal comprises a transmitter, a receiver and acontroller and is configured to communicate wirelessly with the basestation and to communicate wirelessly with the mobile node, the methodcomprising: the terminal activating a limited local radio connectionbetween the terminal and the mobile node; the terminal starting a firsttimer of fixed duration when or after the limited local radio connectionis activated; and when the timer has expired, the terminal activating alimited base station radio connection between the terminal and the basestation and terminating the limited local radio connection between theterminal and the mobile node.

According to a fifth example aspect there is provided a terminal for usein a mobile telecommunications network comprising a base stationproviding wireless connectivity within a base station cell, and a mobilenode providing wireless connectivity within a local cell and configuredto communicate wirelessly with the base station, wherein the terminalcomprises a transmitter, a receiver and a controller and is configuredto communicate wirelessly with the base station and to communicatewirelessly with the mobile node, wherein the terminal is furtherconfigured to: activate a limited local radio connection between theterminal and the mobile node; start a first timer of fixed duration whenor after the limited local radio connection is activated; and when thetimer has expired, activate a limited base station radio connectionbetween the terminal and the base station and terminating the limitedlocal radio connection between the terminal and the mobile node.

According to a sixth example aspect there is provided circuitry for aterminal for use in a mobile telecommunications network comprising abase station providing wireless connectivity within a base station cell,and a mobile node providing wireless connectivity within a local celland configured to communicate wirelessly with the base station; whereinthe circuitry comprises a controller element and a transceiver elementconfigured to operate together to: activate a limited local radioconnection between the terminal and the mobile node; start a first timerof fixed duration when or after the limited local radio connection isactivated; and when the timer has expired, activate a limited basestation radio connection between the terminal and the base station andterminating the limited local radio connection between the terminal andthe mobile node.

According to a seventh example aspect there is provided a method ofoperating a mobile node in a mobile telecommunications networkcomprising a base station providing wireless connectivity within a basestation cell, the mobile node which is configured to provide wirelessconnectivity within a local cell and configured to communicatewirelessly with the base station, and a terminal configured tocommunicate wirelessly with the base station and configured tocommunicate wirelessly with the mobile node, the method comprising themobile node: activating wireless connectivity to the terminal within thelocal cell; starting a timer of fixed duration when or after wirelessconnectivity is activated; and when the timer has expired, terminatingthe wireless connectivity to the terminal within the local cell.

According to an eighth example aspect there is provided a mobile nodefor use in a mobile telecommunications network comprising a base stationproviding wireless connectivity within a base station cell, the mobilenode which is configured to provide wireless connectivity within a localcell and configured to communicate wirelessly with the base station, anda terminal configured to communicate wirelessly with the base stationand configured to communication wirelessly with the mobile node, themobile node comprising a transmitter, a receiver and a controller, andfurther configured to: activate wireless connectivity to the terminalwithin the local cell; start a timer of fixed duration when or afterwireless connectivity is activated; and when the timer has expired,terminate the wireless connectivity to the terminal within the localcell. According to a ninth example aspect there is provided circuitryfor a mobile node for use in a mobile telecommunications networkcomprising a base station providing wireless connectivity within a basestation cell, the mobile node, and a terminal configured to communicatewirelessly with the base station and configured to communicatewirelessly with the mobile node, circuitry comprising a controllerelement and a transceiver element configured to: operate together toprovide wireless connectivity within a local cell and to communicatewith the base station; activate wireless connectivity to the terminalwithin the local cell; start a timer of fixed duration when or after thewireless connectivity to the terminal within the local cell isactivated; and when the timer has expired, terminate the wirelessconnectivity to the terminal within the local cell.

According to a tenth example aspect there is provided a method ofoperating a base station in a mobile telecommunications network, thebase station comprising a transmitter, a receiver and a controller andbeing configured to provide wireless connectivity within a base stationcell, the mobile telecommunications network comprising the base station,a mobile node providing wireless connectivity within a local cell andconfigured to communicate wirelessly with the base station, and aterminal configured to communicate wirelessly with the base station andconfigured to communicate wirelessly with the mobile node, the basestation further configured to: activate a limited base station radioconnection between the terminal and the base station when a timer offixed duration has expired after having been started in response toactivation of a limited local radio connection between the terminal andthe mobile node.

According to an eleventh example aspect there is provided a base stationfor use in a mobile telecommunications network comprising the basestation, a mobile node providing wireless connectivity within a localcell and configured to communicate wirelessly with the base station, anda terminal configured to communicate wirelessly with the base stationand configured to communicate wirelessly with the mobile node, the basestation comprising a transmitter, a receiver and a controller and beingconfigured to: provide wireless connectivity within a base station cell;and activate a limited base station radio connection between theterminal and the base station when a timer of fixed duration has expiredafter having been started in response to activation of a limited localradio connection between the terminal and the mobile node.

According to a twelfth example aspect there is provided circuitry for abase station for use in a mobile telecommunications network comprisingthe base station, a mobile node providing wireless connectivity within alocal cell and configured to communicate wirelessly with the basestation, and a terminal configured to communicate wirelessly with thebase station and configured to communicate wirelessly with the mobilenode, the circuitry comprising a controller element and a transceiverelement configured to: provide wireless connectivity within a basestation cell; and activate a limited base station radio connectionbetween the terminal and the base station when a timer of fixed durationhas expired after having been started in response to activation of alimited local radio connection between the terminal and the mobile node.

According to a thirteenth example aspect and to a fourteenth exampleaspect there are respectively provided computer software which, whenexecuted by a computer causes the computer to perform any of the abovemethods (and any of their variations falling within the scope of theclaims), and a storage medium which stores the computer software.

Further respective aspects and features are defined in the appendedclaims.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary, but are notrestrictive, of the present technology. The described embodiments,together with further advantages, will be best understood by referenceto the following detailed description taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the disclosure and many of the attendantadvantages thereof will be readily obtained as the same becomes betterunderstood by reference to the following detailed description whenconsidered in connection with the accompanying drawings wherein likereference numerals designate identical or corresponding parts throughoutthe several views, and wherein:

FIG. 1 shows a schematic diagram of an example mobile telecommunicationsnetwork or system;

FIG. 2 shows a schematic representation of an example local cellarrangement;

FIG. 3 shows a schematic representation of an example cell arrangementcontaining a hot spot;

FIG. 4 shows a schematic representation of the example cell arrangementof FIG. 3 in which a local cell has been set up;

FIG. 5 shows a schematic representation of the example cell and localcell of FIG. 4 at a later time;

FIG. 6 shows a schematic representation of the example cell and localcell of FIG. 4 at a still later time;

FIG. 7 shows a flow chart of steps in an example method for managingradio connections of a terminal in a local cell;

FIG. 8 shows a flow chart of steps in an example method for managing thelifetime of a local cell;

FIG. 9 schematically depicts example radio state transitions of aterminal in a cell and a local cell;

FIG. 10 schematically depicts example operational transitions of aterminal in a cell;

FIG. 11 shows a flow chart of steps in an example method for operating alocal cell;

FIG. 12 shows a schematic representation of the example cell and localcell of FIG. 4 after movement of a user equipment;

FIG. 13 shows a schematic representation of the example cell and localcell of FIG. 4 after movement of the virtual cell user equipment;

FIG. 14 shows a flow chart of steps in an example method for managingmobility in a virtual cell context;

FIG. 15 shows a flow chart of steps in an example method for use in amobile telecommunications system or network; and

FIG. 16 shows a schematic representation of an example terminal and anexample base station in a telecommunications system or network.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 1 shows a schematic diagram illustrating some basic functionalityof a mobile (cellular) telecommunications network/system, in thisexample operating generally in accordance with LTE principles, and whichmay be adapted to implement embodiments of the disclosure as describedfurther below. Various elements of FIG. 1 and their respective modes ofoperation are well-known and defined in the relevant standardsadministered by the 3GPP® body, and also described in many books on thesubject, for example, Holma, H. and Toskala, A. [1]. It will beappreciated that operational aspects of the telecommunications networkwhich are not specifically described below may be implemented inaccordance with any known techniques, for example according to therelevant standards and known variations thereof. Furthermore, it will beappreciated that whilst some specific examples described herein mayrefer to implementations based around particular 3GPP implementations,the same principles can be applied regardless of the underlyingoperating principles of the network. That is to say, the same principlescan be applied for wireless telecommunications networks operating inaccordance with other standards, whether past, current or yet to bespecified.

The network in FIG. 1 includes a plurality of base stations 101connected to a core network 102. Each base station provides a coveragearea or cell 103 within which data can be communicated to and fromterminal devices 104. Data is transmitted from base stations 101 toterminal devices 104 within their respective coverage areas 103 via aradio downlink DL. Data is transmitted from terminal devices 104 to thebase stations 101 via a radio uplink UL. The uplink and downlinkcommunications are made using radio resources that may be used by theoperator of the network. The core network 102 routes data to and fromthe terminal devices 104 via the respective base stations 101 andprovides functions such as authentication, mobility management, chargingand so on. In addition to the base stations 101 and terminal devices104, the system may further comprise one or more relay nodes/devices.These may be used to enhance coverage for terminal devices operating inthe relevant cell(s). The deployment of relay nodes (e.g. in terms oftheir locations) may follow generally established techniques for usingrelay nodes to support coverage in wireless telecommunications systemsby assisting downlink and/or uplink communications. Regardingterminology, terminal devices may also be referred to as mobilestations, user equipment (UE), user terminal, terminal, mobile radio,mobile terminal, mobile device and so forth. Base stations may also bereferred to as transceiver stations, nodeBs, e-nodeBs, eNBs and soforth. Relay nodes may also be referred to as relay devices, relays, andso forth. In some example implementations of the present disclosure, aterminal device may be operating as a relay node to assist in supportingcommunications associated with other terminal devices. That is to say,the functionality of a relay device may be provided by a suitablyconfigured terminal device.

Mobile telecommunications systems such as those arranged in accordancewith the 3GPP defined Long Term Evolution (LTE) architecture use anorthogonal frequency division multiplex (OFDM) based interface for theradio downlink (so-called OFDMA) and the radio uplink (so-calledSC-FDMA).

It has been suggested that a UE might operate to provide a local cell orvirtual cell (VC), whereby the UE will operate as an intermediate nodebetween other UEs in its vicinity and the network (for example a basestation), as well as an intermediate node between UEs. The UE maycommunicate with neighbouring UEs and provide them with connectivity tothe base station (e.g. to reach the core network) and potentially toother neighbouring UEs as well. The UE provides the functions of a basestation to the neighbouring UEs within its virtual cell coverage range.

FIG. 2 schematically represents an example local cell arrangement. Abase station eNB provides connectivity in a cell 203 (sometimeshereinafter referred to as a “base station cell” or simply “cell” if itis clear from the context that the cell is provided by a base station).At the same time, a UE operates as a “VC-UE” (for Virtual Cell UE) toprovide connectivity via a virtual cell or local cell 213. In theexample of FIG. 2 , the VC-UE provides mobile connectivity to the threeterminals UE1-UE3 while terminal UE4 is connected directly to the basestation. In this example, only one virtual cell is provided in the cellalthough in some examples more VC may be activated, or no VC may beactivated. In the following, “VC”, “virtual cell” or “local cell” maysometimes be used interchangeably with “VC-UE” (or “mobile node” orequivalents), particularly with reference to functionality andoperability.

Within a local cell, the VC-UE provides a UE with a wirelessconnectivity to the base station, for example to reach the core networkor a remote destination outside of the mobile network (e.g. a publicserver available from the internet). The UE is connected to the VC-UEand uses it as if it were a base station and the VC-UE sends themessages to the base station if need be (e.g. messages for a remotedestination, the base station, the core network, etc.), thereby offeringconnectivity to the base station. Additionally or alternatively, theVC-UE can offer local connectivity to UEs in the local cell. Forexample, if two UEs in the local cell wish to communicate with eachother, the VC-UE can identify that the destination for the messages iswithin its local cell and send the messages directly to the destination.This feature can assist in offloading some of the traffic and trafficmanagement load of the base station.

A VC-UE may communicate with UEs in its local cell using a wirelessinterface provided on one or more unlicensed, shared licensed and/orlicensed bands, and may backhaul traffic to the network in any suitableway, although it is generally expected that this would be carried outusing one or more licensed bands, for example to providing thebackhauling over a wireless interface with a higher interferencecontrol.

A VC-UE is in effect a UE designated to provide a virtual cell functionby working also as an intermediate node between UEs in its vicinity andthe network, as well as an intermediate node between UEs. Note that theVC-UE does not operate in the same manner as a terminal-to-base stationrelay node as currently discussed in the 3GPP consortium, however. Ineffect such a relay is for relaying messages to the base station wherethe terminal is connected as an RRC (radio resource control) layer withthe base station, but not with the relay node. In a virtual cell, theterminal is connected to the “relay” (VC-UE), which therefore operatesmore like an anchor than like a relay (in view of the present definitionand use of 3GPP relays). With this type of service, it is envisaged thatVC-UEs could manage certain aspects such as one or more of radioresource management, RRC connection control and the like, instead ofreliance on the base station only for these aspects. A VC-UE may beexpected not only to relay data but also to organize its own localnetwork/cell from a radio/connection control perspective. The inclusionof such VC-UEs in a network may improve operational aspects, such asoffloading some signalling overhead or resources allocation functionsfrom the base station or by improving the efficiency of radio resourceallocation, amongst other things.

In the context of 3GPP, a terminal and a base station can be either notconnected, in a “RRC_IDLE” state, or in a “RRC_CONNECTED” state.Generally a terminal camping on a cell will be in RRC_IDLE, and when itwants to send data (user data) to the base station, it will transitioninto the RRC_CONNECTED state. Once data transmission is complete, theterminal can revert to RRC_IDLE. The base station maintains RRCconnection context information for all terminals in its cell that arecommunicating with/through it. According to the current 3GPP TechnicalSpecification document 36.331 [2], the RRC_IDLE and RRC_CONNECTED statesare defined as follows:

RRC_IDLE:

-   -   A UE specific DRX [Discontinuous Reception] may be configured by        upper layers.    -   UE controlled mobility;    -   The UE:        -   monitors a Paging channel to detect incoming calls, system            information change, for ETWS [Earthquake and Tsunami Warning            System] capable UEs, ETWS notification, and for CMAS            [Commercial Mobile Alert Service] capable UEs, CMAS            notification;        -   performs neighbouring cell measurements and cell            (re-)selection;        -   acquires system information; and        -   performs logging of available measurements together with            location and time for logged measurement configured UEs.            RRC_CONNECTED:    -   Transfer of unicast data to/from UE.    -   At lower layers, the UE may be configured with a UE specific        DRX.    -   For UEs supporting CA [Carrier Aggregation], use of one or more        SCells [Secondary Cells], aggregated with the PCell [Primary        Cell], for increased bandwidth;    -   For UEs supporting DC [Dual Connectivity], use of one SCG        [Secondary Cell Group], aggregated with the MCG [Master Cell        Group], for increased bandwidth;    -   Network controlled mobility, i.e. handover and cell change order        with optional network assistance (NACC [Network Assisted Cell        Change]) to GERAN [GSM/EDGE Radio Access Network];    -   The UE:        -   monitors a Paging channel and/or System Information Block            Type 1 contents to detect system information change, for            ETWS capable UEs, ETWS notification, and for CMAS capable            UEs, CMAS notification;        -   monitors control channels associated with the shared data            channel to determine if data is scheduled for it;        -   provides channel quality and feedback information;        -   performs neighbouring cell measurements and measurement            reporting; and        -   acquires system information.

The RRC_IDLE state can be thought of as a limited or low radioconnection, and the RRC_CONNECTED state can be thought of as a full orhigh radio connection. The present disclosure is equally applicable tomobile telecommunications systems using these states within the 3GPParchitecture and to other comparable limited states and full statesdefined within other telecommunications architectures and protocols.Accordingly, radio resource control states may be defined for theterminal to have a full connection or a limited connection with thelocal cell and/or a full connection or a limited connection with thebase station. As used herein, a “full” connection or a terminal being“fully” connected with one of a mobile node or a base station refers toa radio resource control (e.g. RRC in 3GPP) state in which the terminalcan (among other functions) exchange user data and signalling with themobile node or base station. A “limited” connection refers to a radioresource control state in which the terminal remains connected to themobile node or base station but cannot exchange user data with themobile node or base station. For example, in a limited mode, theterminal may be configured to do one or more of: monitoring andreceiving paging information, carrying out measurements, handlingmobility (e.g. to another virtual cell or base station cell), and thelike. Furthermore, in a limited mode the terminal may be able to receivedata in a broadcast manner such as by MBMS (Multimedia BroadcastMulticast Services) or eMBMS (evolved MBMS).

In accordance with the present disclosure, various uses are made of thedifferent connection states to facilitate efficient radio resourcemanagement in a virtual cell context, in which some of thefunctionalities of the base station can be transferred to a mobile nodeproviding a local (virtual) cell. In a 3GPP environment this relies ondifferent levels of RRC connectivity with the mobile node and with thebase station.

A virtual cell arrangement of this type, and as further proposed herein,in which an RRC connection can be established between a VC-UE and a UE,may be of benefit in with the following situations, in particular in a3GPP environment (although the same teachings could be transposed to adifferent environment):

-   -   A RRC signalling overhead reduction between the base station and        UE. In conventional network architectures, the eNB is        responsible for maintaining the RRC connections with all UEs        within coverage, and the signalling overhead can be        non-negligible in a UE-dense scenario. Furthermore, taking into        account possible massive connections from IoT (Internet of        Things) MTC (machine-type communications) devices with sensors        to the eNB, the signalling overhead may cause critical issues on        the current network architecture. In accordance with the present        disclosure, a reduction in signalling may be attempted by        selecting and activating one or more virtual cells within the        base station cell, and allowing each virtual cell to manage the        RRC connections with the UEs in that virtual cells. The base        station no longer needs to maintain full RRC connections with        every UEs individually and can instead maintain a limited or        partial RRC connection with the UEs.    -   An improvement in spectrum efficiency and interference        mitigation by supporting resource allocation within the virtual        cells. Compared with resource allocation managed by a single        node (base station), a distributed resource allocation scheme        using one or more virtual cells can provide more flexibility and        robustness. For example, through coordination with virtual cells        in the network, the eNB may have a better control of the        interference mitigation and resource management across the        entire base station cell, and can control resources allocated to        the VC with a view to reducing inter-virtual cell interferences.        Owing to the (expected) lower transmission power of VCs, the        same resources might be shared among different VCs to further        improve the spectrum efficiency. It can be more straightforward        to manage a smaller group of UEs (compared to the large of        number of UEs that a base station is generally expected to        manage), and this may be done with a relatively fine granularity        of resources to allocate to UEs in a VC range. This can in turn        be expected to reduce intra-virtual cell interferences (with a        finer granularity in the resource allocation, the number of        resource units that can be allocated is expected to increase        such that the probability of users sharing the same resources        will decrease). Accordingly, the mobile node (VC-UE) can        beneficially manage resource allocation for the UEs in its local        cell. The RRC connections may be managed by the mobile node to        configure/re-configure the related physical control channels and        data channels for example to receive resource allocation grants        and data, respectively, as well as other configurations to        support the resource allocation, such as Buffer Status Report        (BSR) timers etc.    -   QoS differentiation. It is expected that, in future networks,        QoS differentiation support will be an important aspect, both        between users and between services for each individual user.        With a RRC connection between the VC and the UE, the resource        can be allocated by the mobile node (VC) for different QoS        classes with a view to improving QoS and/or quality as perceived        by the user. The virtual cell can then manage the corresponding        radio bearers with the UE (e.g. to establish/maintain/release        them) for mapping the logical channel configuration with the        services. Owing to the RRC connection between the virtual cell        and the UE, such a resource allocation management can be        provided, if appropriate.    -   An improvement of spectrum efficiency and service continuity by        supporting measurement report transmission. With a view to        improving the local resource allocation by the virtual cell, the        virtual cell may be made aware of the quality between virtual        cell and its scheduling UE. The UE may then measure the channel        quality with the mobile node providing the virtual cell and        report this to virtual cell if being triggered (events can be        defined for example if the link quality is too low, relatively        lower than with another mobile node providing another virtual        cell, relatively lower than with the base station, etc.). Using        the RRC connection between virtual cell and the UE, the        measurements can be configured and transmitted to the virtual        cell in a measurement report.

While the local cells are expected to assist the base station, they arealso expected to be of a more transient nature than a base station, andeven more so if they are provided by a terminal which may be mobile, runout of battery, etc. In common with a eNB, however, the virtual cellneeds to manage its RRC connections to UEs, and it may be desired toutilise conventional RRC procedures as much as possible. Note that inthe present context, the virtual cell may be established on a UE, or arelay node with mobility.

From the foregoing it will be appreciated that it is necessary toconsider how a virtual cell manages to set up, maintain and release theRRC connection with its UEs (RRC state management), and how or when theoperation of the virtual cell may be activated and terminated. Theseissues are considered further herein.

In a situation where a cell experiences a high density of UEs, it may bedesirable to improve the cell capacity. If UEs which are connected tothe eNB are concentrated in some area within the cell, it is efficientto establish a virtual cell in that area in an on-demand manner inresponse to the concentrated demand so as to improve cell capacitytemporarily. The virtual cell can be terminated when the concentrationhas dispersed. A known approach to improving cell capacity uses relaytechnology, but a relay as specified, for example, in 3GPP Release 10,is assumed to have a fixed location, and hence is not alwaysconveniently placed to address a dynamic UE concentration.

FIG. 3 shows a schematic representation of a cell in which a virtualcell may be implemented. The cell 303 is served by an eNB (basestation), and at the depicted moment, includes five UEs within itscoverage. Four of theses, UE1-UE4, are connected to the eNB for datatransfer (such as by a full RRC or RRC-like connection, designatedherein as an RRC_CONNECTED state), and happen to be concentrated in asmall area (relative to the size of the cell 303). This circumstance, inwhich data traffic is spatially concentrated, may be termed a “hotspot”. The fifth terminal, UE5, is in the same area, but does notcontribute to the hot spot since it is not RRC_CONNECTED to the eNB, butis rather in a idle state, not sending or receiving data. Forsimplicity, FIG. 3 shows an example which has only one hot spot in thecoverage of the eNB, but in reality many hot spots may arise. Under suchconditions, the eNB could face a lack of radio resources and an overloadof signalling to the UEs in the cell. To address this, a virtual cellmay be activated.

FIG. 4 shows a schematic representation of the cell 303 of FIG. 3 aftera virtual cell has been established. The virtual cell is based on a UEwhich temporarily operates as base station in an on-demand manner, inresponse to the hot spot. The eNB recognises a hot spot, based on itsbuffer status, or as reported to it by the connected UEs, for example,and identifies a UE in the hot spot locality which is in an idle state(having a limited RRC or RRC-like connection, designated herein asRRC_IDLE). Note that if a UE is in an idle state but is involved in MBMSor eMBMS communication, it preferably should not be selected. In thepresent example, UE5 is a suitable candidate terminal. The eNB thenindicates to UE5 (or another suitably located terminal in RRC_IDLE) thatit should operate as a virtual cell. When the UE in RRC_IDLE is notifiedto operate as a virtual cell by the eNB, RRC connection is establishedbetween the eNB and the UE in RRC_IDLE, and the UE transitions from itsRRC_IDLE state to be RRC_CONNECTED with the eNB since this is necessaryfor the terminal to host a virtual cell. An interface between the eNBand the virtual cell (UE5) is activated for operation of the virtualcell; this may be the Un interface for relay node operation specified by3GPP Release 10, or a new format of virtual cell interface yet to bespecified, or any other suitable past or current interface. Aftersetting up the virtual cell operation, the eNB performs procedures tocause the UEs in the hot spot, UE1-UE4, to handover from the eNB to thevirtual cell. The network may control some prioritization of UE handoverso as to avoid an excessive number of simultaneous handovers. Forexample the network may give higher prioritization to UEs which areperforming higher QoS communications, large data communication, or thelike. The procedures may include RRC Connection Setup, RRC ConnectionReconfiguration and RRC Connection Re-establishment messages toconfigure the UEs to send Measurement Report messages which includemeasurements of the link quality between the UEs and the virtual cell aswell as that between the UEs and the eNB. Furthermore, thisconfiguration of measurement may be defined by Measurement Objects,Reporting Configurations, Measurement Identities, QuantityConfigurations and Measurement Gaps, and the virtual cell may beincluded in a list of candidate cells to be measured as MeasurementObjects. In this context the Un interface could support protocol stacksfor S1 interface and X2 interface, so that the virtual cell may exchangeany information related to load balancing and interference with the eNB.Thereby, the virtual cell can be enabled to perform resource managementand ICIC (Inter Cell Interference Coordination) or eICIC (enhanced ICIC)so as to maximize efficiency of usage of radio resources under the hotspot condition. After handover, the virtual cell 313 is establishedbased on the UE5, which becomes a virtual cell UE (VC-UE), and the UEswhich have been handed over to the VC-UE are in a RRC-CONNECTED statewith the VC-UE and able to continue participation in data trafficpreviously enabled by the RRC connection to the eNB. So, each UE isRRC_CONNECTED with the VC-UE (VC_RRC_CONNECTED), and the VC-UE isRRC_CONNECTED with the eNB. Note that in the interests of conciseness,RRC or RRC-like connections with a mobile node or VC-UE are referred toherein as “VC_RRC”, and RRC or RRC-like connections with the basestation are referred to herein as “RRC”. This should not be understoodas referring to the RRC defined in the 3GPP only, but rather is equallyapplicable to corresponding radio resource control connections providingat least the same or similar functionalities. In one example, thefunctionalities available in the VC_RRC_IDLE and VC_RRC_CONNECTED statesare defined as follows:

VC_RRC_IDLE

-   -   Sleeping mode management for energy saving/DRX management    -   VC specific system information acquisition (if any)    -   measurements configuration from the VC    -   paging channel—if any—monitoring        VC_RRC_CONNECTED    -   Data transfer between UE and VC    -   Energy saving mode/DRX management    -   Mobility control, handover to another VC or fallback to network    -   paging channel—if any—monitoring    -   VC specific system information acquisition (if any)    -   Monitoring of the VC's specific control channel and data channel        to send/receive data    -   Perform measurement if configured by the VC    -   Provide channel state information for the VC and feedback if        necessary

The initial condition of VC_RRC_CONNECTED UEs throughout the virtualcell preferably should not and possibly cannot be maintainedindefinitely. The VC-UE and the UEs are all mobile and have finite poweravailable to them so the connection states and configuration shown inFIG. 4 may become impractical. Therefore, it is proposed that a UE whichhas RRC connection to the virtual cell will transition to be in RRC_IDLEafter it has finished transmission or reception of data to or from thevirtual cell to save power consumption. This is similar to usualprocedures outside of a virtual cell in which a UE not engaged in datatraffic keeps an RRC_IDLE connection to a eNB. Furthermore, since thevirtual cell is set up to improve cell capacity under a hot spotcondition, if or when the hot spot condition ceases (the concentrationof RRC-CONNECTED UEs has dispersed or switched to RRC_IDLE), the virtualcell will have fewer UEs in VC_RRC_CONNECTED. This may be wasteful ofradio resources for reference signals and the like, and if resources arepooled for the virtual cell in collaboration with the eNB, the eNB mayhave limited access to radio resources which are no longer needed by thevirtual cell. To address this, the virtual cell may stop operating, forexample by the VC-UE turning back to be a regular UE in RRC_IDLE withthe eNB. Example procedures for implementing these transitions arediscussed further below.

FIG. 5 shows a schematic representation of the cell 303 and virtual cell313 after a first UE has completed its current data transfer. In thisexample UE2 has finished a transmission/reception of data to/from thevirtual cell 313, and has switched to be in RRC_IDLE so to reduce powerconsumption. However, taking into account that UE2 may need torecommence transmission/reception of data to/from the virtual cell atshort notice, UE2 has its RRC_IDLE state with respect to the virtualcell (i.e. VC_RRC_IDLE, represented by a dotted line). Under this state,the virtual cell can send RRC Connection Release messages to UE2 andperform a UE Context Release procedure with a MME (mobility managemententity) in the same or similar manner as a conventional eNB or relaynode do. If UE2 then requires to engage in data traffic again, from theVC_RRC_IDLE state it requests an RRC connection to the virtual cell, andis enabled to transition back to VC_RRC_CONNECTED and starttransmission/reception of data to/from the virtual cell, reverting tothe system as depicted in FIG. 4 .

However, in the event that no further data traffic is required by UE2 oranother UE in the virtual cell that is sitting in VC_RRC_IDLE, the UEmay remain in VC_RRC_IDLE for a relatively long time. If this occurs,the UE faces an increased possibility of losing the virtual cell, sincethe VC-UE is mobile and may move such that the UE is outside coverage ofthe virtual cell. The virtual cell will then not be available if datatransfer becomes necessary. To address this, it is proposed that the UEswitches from VC_RRC_IDLE, i.e. an idle state with the VC_UE, toRRC_IDLE, i.e. an idle state with the eNB. The UE thus ceases to beincluded in the virtual cell and instead can rely on the eNB for a nextdata transfer. FIG. 6 shows a schematic representation of the cell 303after this transition has been made. UE2 no longer has any connectivitywith the virtual cell, and instead has a RRC_IDLE connection with theeNB, indicated by the dotted line.

FIG. 7 shows a flow chart of steps in an example method for implementingthis transition for a UE within a virtual cell. After termination of theinitial VC_RRC_CONNECTED state, a UE enters the VC_RRC_IDLE state(S101). Also, a timer is reset and started counting (S102). This is atimer for VC_RRC_IDLE operation, and may be maintained by the UE or bythe VC-UE. The timer has a particular duration, and this duration may bepredetermined (fixed and set in advance, such as during manufacture ormaintenance/upgrading of the UE or VC_UE), or configured on demand bythe virtual cell, for example based on a size of coverage of the virtualcell (which depends on the output power of the VC_UE) and/or the bufferstatus of the virtual cell or the eNB at the time. The timer may bestarted simultaneously with entry into the VC_RRC_IDLE state, or afterentry in the VC_RRC_IDLE, for example a fixed time afterwards. The fixedtime may be a short time, for example less than 30 seconds or less thanone minute, or a longer time, such as more than one minute. Next, the UEjudges whether it needs to perform a transition from VC_RRC_IDLE toVC_RRC_CONNECTED, for example if data transfer is required (S103). Ifyes (a full connection is required), the UE makes the transition to theVC_RRC_CONNECTED state (S104) and stops the VC_RRC_IDLE state. Also, thetimer is stopped and the method ends. If the judgement in step S103 isno (a full connection not required), the UE keeps counting the timer(S105). Then a judgement is made as to whether the timer has expired(S106). If no, the UE returns to step S103 and the procedure continuesas before. If the timer is found to have expired in step S106 (the timerduration has been met), the UE makes a transition to an RRC_IDLE statewith the eNB (S107), and leaves its VC_RRC_IDLE state, and the methodstops. The finishing of the idle (limited) radio state with the VC_UEand the starting of the idle (limited) state with the eNB may beperformed simultaneously or sequentially. If sequentially, either actionmay occur first, but if the RRC_IDLE state to the eNB is activatedbefore the VC_RRC_IDLE state is terminated, a radio connection ismaintained at all times. If desired, the UE may perform a cellreselection procedure prior to executing S107, in which it decides whicheNB (or possibly a VC-UE if there is an alternative virtual cell nearby)to connect with. This cell reselection may be performed after excludingthe current virtual cell from a list of candidate cells or adding thecurrent virtual cell to a list of blacklisted cells, so as to avoidreconnection to the current virtual cell. The method may be configuredsuch that one or both of the judgement steps S103 and S106 are performedonly at specific time intervals (i.e. at a predetermined frequency) toreduce processing overhead in execution of the method.

A second timer may be utilised to manage the lifetime of the virtualcell. This may be in conjunction with or separately from the use of afirst timer for VC_RRC_IDLE operation for one or more UEs in the virtualcell. FIG. 8 shows a flow chart of steps in an example method forcontrolling start and stop times for operation of a virtual cell.Firstly, a UE (such as UE5 in FIG. 3 ) starts operation of a virtualcell (S201). Then the virtual cell resets a timer to t=0 and starts thetimer (S202). The timer is for virtual cell operation and may bemaintained by the VC-UE or the eNB. The timer has a defined duration,which may be predetermined (fixed and set in advance, such as duringfabrication, maintenance or upgrading of the VC-UE or the eNB), orconfigured on demand by the eNB, for example based on a size of coverageof the virtual cell (which depends on the output power of the VC-UE)and/or the buffer status of the virtual cell or the eNB at the time. Thetimer may be started simultaneously with the commencement of virtualcell operation, or after virtual cell commencement, for example a fixedtime afterwards. The fixed time may be a short time, for example lessthan 30 seconds or less than one minute, or a longer time, such as morethan one minute In a next step S203, while the timer is running, thevirtual cell makes a judgement about whether it has performed, handledor managed any data transmission or reception since the timer wasstarted. If the answer is yes (transmission or reception has occurred),the virtual cell resets and restarts the timer (S204) and return todecision step S203. On the other hand, if no transmission or receptionhas happened so that the judgement answer in S203 is no, the virtualcell keeps counting (running) the timer (S205). Subsequently, thevirtual cell judges whether the timer has expired or not (S206), i.e. ifthe timer has run for its full duration. If no (the timer is stillrunning), the method returns to step S203 for further judgement aboutdata activity. If yes at S206 (the timer has expired), the virtual celloperation is terminated, by stopping operation of the VC-UE as a virtualcell hub, and returning it to standard operation as a UE (S207). Forexample, this could be a state of RRC_IDLE of the UE to the eNB. Themethod may be configured such that one or both of the judgement stepsS203 and S206 are performed only at specific time intervals (i.e. at apredetermined frequency) to reduce processing overhead in execution ofthe method.

Upon closure of the virtual cell, it may occur that one or more UEs inthe virtual cell are in a VC_RRC_IDLE state with the VC-UE. This can beaddressed by configuring the timer for virtual cell operation (secondtimer) to have a duration equal or longer than the duration of the timerfor VC_RRC_IDLE operation (first timer). Under this arrangement, all UEsin VC_RRC_IDLE under the virtual cell will have already made thetransition to RRC_IDLE to the eNB before operation of the virtual cellis terminated. If the UEs in the virtual cell are able to have differentdurations of first timer (for example, if the timers are set on demandin response to a parameter that might alter over time, such as bufferstatus), a maximum allowable first timer duration can be established,and the second timer duration set to be equal to or longer than themaximum first timer duration. According to this procedure, a VC-UE thathas been established in an on-demand manner in response to aconcentration in demand can be efficiently released once the hot-spotcondition is resolved.

FIG. 9 is a schematic representation of possible state transitions for aUE operating in a cell and a virtual cell. Arrows connecting the variousstates indicate allowable directions of transition. A UE may initiallybe in an RRC_IDLE state to a eNB (S301). The UE may request a full RRCconnection to the eNB (for example if a need for data traffic arises),so that the UE turns to be in RRC_CONNECTED with the eNB (S302). Whilstit is in RRC_CONNECTED, it may contribute to a hot spot that causes theeNB to set up a virtual cell based on an idle UE in or near the hot spotarea. The eNB may then request the UE to handover to the virtual cell,so that the UE performs a handover procedure to join the Virtual Celland transitions to be in VC_RRC_CONNECTED (S303). Here, the eNB mayconfigure measurement reporting by the UE (such as byRRC_Connection_Configuration messaging) for use in a decision procedurefor handover from the virtual cell (which is discussed further below).Following this, the UE in VC_RRC_CONNECTED might need to handover backto the eNB (revert to RRC_CONNECTED), for example due moving outside thevirtual cell coverage (S302). Alternatively, while in VC_RRC_CONNECTEDif the UE finishes transmission or reception of data with the virtualcell, the UE turns to be in VC_RRC_IDLE (S304), equivalent to theconventional RRC management procedure of the eNB (from S302 to S301).Then while in VC_RRC_IDLE, if the UE does not request an RRC connectionto the virtual cell to perform transmission/reception of data to/fromthe virtual cell (from s304 to S303) for the predetermined or configuredduration of the first timer (following the method of FIG. 7 ), the UEtransitions to be in RRC_IDLE to the eNB (S301). The state transitionfrom S304 to S301 can also take place if the UE moves out of coverage ofthe virtual cell while in VC_RRC_IDLE. A possibility of failure of thelink between the UE and the virtual cell caused by mobility of thevirtual cell while the UE is in VC_RRC_IDLE (so that the VC_UE and/orthe eNB may no longer be able to track the presence of the UE inside theVC-UE coverage) can be addressed by limiting a duration of theVC_RRC_IDLE state, such as by using the first timer described above.

The tasks which a UE may basically perform during the VC_RRC_IDLE andVC_RRC_CONNECTED states may be the same as or similar to those which theUE performs during RRC_IDLE and RRC_CONNECTED states (as defined forexample in the current 3GPP Technical Specification document [2]). Inother words, operation of the UE within a virtual cell can besubstantially the same as its operation within a base station cell.

FIG. 10 is a schematic representation of possible state transitions fora UE configured to operate on demand as a VC-UE to establish a virtualcell. Note that a UE which supports the functionality of operating avirtual cell should also support the state transitions shown in FIG. 9 ,for times when it is operating as a standard UE and not as a VC_UE.

A UE is initially in RRC_IDLE to a eNB and operating as a UE (S401). Ifthe eNB requests the UE to operate as virtual cell (for example inresponse to a hot spot arising in the vicinity of the UE), the UEtriggers appropriate procedures for virtual cell operation. Theseprocedures include the establishment of RRC connection to the eNB atleast (RRC_CONNECTED). At the same time or after establishment of RRCconnection to the eNB, the UE may activate virtual cell functionalityimplemented in it or configured by the network, and establish therequired interface between the virtual cell and the eNB. As mentionedearlier this interface may be the Un interface specified for relay nodeoperation in 3GPP Release 10, or any known or new interface for virtualcell operation that might be developed in the future. As a result ofthese actions, the UE transitions to be in the virtual cell operationstate (S402). This state should be RRC_CONNECTED from the perspective ofthe eNB. Once in virtual cell operation, the VC-UE may make thetransition back to UE operation in RRC_IDLE (S401) due to mobility(movement out of range of the UEs or the eNB), condition of data trafficin the eNB's cell (dispersal of the UEs forming a hot spot, for example)and so on, as described above. Before making the transition back to aregular UE, the virtual cell may perform handover procedure for UEsbelonging to it so that those UEs can handover to another virtual cellor the eNB.

We can also consider the possibility that concentration of data trafficin a hot spot may be periodic to some extent. For example, the hot spotcondition may re-occur relatively quickly after the virtual cell hasceased operation. In this context it may be useful, before the VC-UEtransitions from RRC_CONNECTED (S402) to RRC_IDLE (S401), for a eDRX(extended Discontinuous Reception) connection to be configured betweenthe eNB and the VC-UE. The eDRX connection may be configured by the eNBor by the VC-UE. This can avoid a need for repeated reactivation of theVC-UE in response to repeated hotspot conditions, and save powerconsumption of the VC-UE. It is proposed that the VC-UE uses the eDRXoperation to keep the RRC_CONNECTED state to the eNB. The VC-UE need notthen have to configure eDRX to an access link whenever a UE requests aconnection set-up to the virtual cell. If the VC-UE receives aconnection set-up request from a UE while in the eDRX condition, theVC-UE can release the eDRX operation of the link between the VC_UE andthe eNB together with the eNB. Also, the VC-UE can reset and start atimer when the eDRX is established. The timer has a defined duration,which may be predetermined (fixed and set in advance, such as duringfabrication, maintenance or upgrading of the VC-UE or the eNB), orconfigured on demand by the eNB, for example based on a size of coverageof the virtual cell (which depends on the output power of the VC-UE)and/or the historical behaviour of data traffic or the eNB up to thattime. For example, an average value of data traffic via the VC-UE indownlink and/or uplink over time might be used to define the historicalbehaviour. When this timer for the eDRX operation expires, thetransition of the VC-UE from RRC_CONNECTED (S402) to RRC_IDLE (S401) canfinally be performed.

FIG. 11 shows a flow chart of steps in an example of such a procedure,which in this case is implemented in conjunction with the virtual celltimer operation method illustrated in FIG. 8 . Steps which are the sameas those in FIG. 8 have the same numbers, and the description of them isnot repeated here. The additional steps relating to the eDRX operationprocedure appear as steps S208 to S213 which are implemented before stepS202 or S203 from the FIG. 8 procedure. In this example, the timer usedfor the virtual cell operation already described above is also employedas the eDRX operation timer. After starting operation of the virtualcell in step S201, the method proceeds to step S208 where the status ofdata traffic in the hot spot area, corresponding to the virtual cellarea, is checked. Following this, in step S209, a judgement check ismade as to whether eDRX operation has already been configured (forexample during a previous loop of the FIG. 11 method)_If it has not, theresult of the data traffic status check from step S208 is then judged injudgement step S210, where the method determines if the amount of datatraffic meets a first condition which tests if the virtual cell shouldenter the eDRX mode. If the level of data traffic is high, for exampleabove a predetermined threshold which can be set according to networkrequirements, there is considered to be no need for eDRX operation, sothe first condition is not met, and the method loops back to step S208for further monitoring of the data traffic status. On the other hand, ifthe level of data traffic is low so that it falls below the threshold,the first condition is met in step S210. The method then moves to stepS211 in which eDRX operation is configured for the link of the VC-UEwith the eNB. Subsequent to the configuration of the eDRX operation instep S211, the method proceeds to step S202 in which the VC-UE resetsand starts the timer before the method moves to step S203 previouslydescribed with respect to FIG. 8 . If in the test in step S209 it isfound that the eDRX operation has already been configured, the methodproceeds to step S212 where a further judgement of the data trafficstatus is made, this time against a second condition. The secondcondition tests whether it is appropriate for the eDRX mode to bereleased. If it is found that the level of data traffic is high, forexample, above a predetermined threshold which can be set according tonetwork requirements, the second condition is met. Hence, it is deemedthat eDRX mode is no longer required, and the method moves to step S213in which the VC-UE releases eDRX operation of its link with the eNB.Then, the method returns to step S208 for continued checking of the datatraffic. Conversely, if it is found in step S212 that the secondcondition is not met, because the data traffic level is below thethreshold, continued eDRX operation is appropriate, and the VC-UEcontinues in this state to follow the method to step S203, previouslydescribed for FIG. 8 . There is no need to start the timer via the stepS202 because it will be already running from a previous loop of themethod in which the existing eDRX operation was configured. Hence,following any of the paths through steps S208 to S213, the method thenproceeds as already described with regard to FIG. 8 . Virtual celloperation is stopped if the timer expires, and if the timer is stillrunning the virtual cell remains operational and continues monitoringfor data transmission or reception (step S203, counting the timer (stepS205) and checking the data traffic status (step S208). If datatransmission or reception is found to have occurred in step S203, thetimer is reset in step S204 and the method returns to step S208 tomonitor the data traffic. This also happens if there has been notransmission or reception but the timer has not yet expired in stepS206.

In this procedure, the first condition in step S210 and the secondcondition in step S212 might be the same (the same threshold for datatraffic level, for example). However, possible ping-pong operation ofthe eDRX link may occur in this case, so it may be appropriate toconfigure the conditions to be different (different thresholds, forexample).

According to the FIG. 11 procedure, the VC-UE or the network canactivate eDRX operation depending on the data traffic condition so as touse radio resources for backhauling efficiently as much as possible. Forexample, multiple VC-UEs may share radio resources for backhauling amongthemselves in a time-sharing manner by setting eDRX operation atdifferent offsets (drxStartOffset) and/or durations (OnDurationperiods).

As described herein, a VC-UE is in essence a UE that is also able tosimultaneously provide the function of a relay node between the eNB anda number of UEs. To achieve this, a suitable interface is activatedbetween the eNB and the VC-UE, which may be, for example, the Uninterface for replay node operation specified by 3GPP Release 10. Thisspecification (“3GPP TS 36.300: 4.7 Support for relaying” [3]) includesthe assumption that the relay node has a subset of UE functionality, butdoes not support an inter-cell handover procedure that can be requiredwhen network components have mobility. A relay node is stationary, sothere is no need to consider procedures related to mobility such asreporting measurements of link quality between the relay node and itseNB (donor eNB). Once the relay node functions are given to a UE forVC-UE operation, however, mobility issues become relevant and one shouldconsider the need to perform mobility management procedures. Forexample, since under Release 10 a relay node can have a subset of UEfunctionality, the procedure of a UE reporting measurements of linkquality (Measurement Report messages) might be adapted to make the relaynode specification more suitable for a VC-UE having mobility.

A need for handover of a device (UE or VC-UE) can arise when that deviceis no longer within the coverage area of the cell in which it has beenoperating. In the context of a virtual cell, two handover situationsshould be considered because both the UE and VC-UE have mobility. The UEmay move out of range of the VC-UE, and need to handover to the eNB (ora different eNB) or to a different virtual cell. The VC-UE may move outof range of the eNB. It will then need to handover to another eNB (orpossibly to a different virtual cell if its virtual cell hosting hasbeen terminated). The virtual cell functionality it has been providingwill cease, and UEs in the virtual cell will also need to handover, tothe eNB or a different virtual cell. It may be considered that handoverof the UE could be managed by the virtual cell, and handover of thevirtual cell could be managed by the eNB. However, the mobility of theVC-UE and the mobility of any UE belonging to it can be dependent oneach other, or independent of each other. Hence, it is useful ifhandovers managed by virtual cells and handovers managed by basestations are not necessarily handled independently. Issues arising fromthis are now considered.

The handover procedures are proposed to be managed by, for example,utilising the Measurement Report messaging procedure. Under RRCprotocols, a device such as a UE can monitor or measure the quality ofradio communication links between itself and other network components,and can be configured or activated to send Measurement Report messageswhich include these link quality measurements. The Measurement Report issent in the uplink direction, from the device to the component providingits cell. In the present context, a UE may be configured to report tothe virtual cell, and the virtual cell may be configured to report tothe eNB. Conventionally, measurement reporting is arranged to betriggered in response to one or more events regarding link quality. Thelink quality reported in this way can be used to determine any need forhandover. This should not be considered as limited to an LTE or other3GPP environment using RRC; examples described herein based onMeasurement Reporting may utilise any link quality measurementprocedure.

FIG. 12 shows a schematic representation of the cell 303 from FIG. 4following motion of a UE. In the example the UE4 has mobility and movesout of the coverage of the virtual cell 313, as indicated by the dottedarrow. In such circumstances, if the UE4 has been sending MeasurementReport messages including measurements of the quality of the radiocommunication link between itself and the VC-UE and itself and the eNB,the virtual cell can determine, based on the reported quality, whetherthe UE4 needs to handover to the eNB or to another virtual cell (notshown). If handover is deemed necessary, the VC-UE can initiate ahandover procedure. FIG. 12 shows that the UE4 has been handed over tothe eNB and is now RRC-CONNECTED thereto, and no longer connected to thevirtual cell.

FIG. 13 shows a schematic representation of the cell 303 from FIG. 4following movement of the UE5 which is providing the virtual cell 313.In this example, the UE5 has moved further from the eNB, as indicated bythe dotted arrow. It is now near the edge of the cell 303, and mayexperience poor radio communication link quality with the eNB. This maymake continued operation of the virtual cell unsustainable. Two handoversituations thereby arise. Firstly, the UE5 operating the virtual cellmay need to handover if the link quality between the eNB and the virtualcell becomes too low. This is Handover Case 1. Secondly, the UEs campingin the virtual cell 313 (UE1-UE4) may need to handover from the virtualcell to the eNB or to another virtual cell (which might be already inoperation or might be newly activated by the eNB or another eNB inresponse to demand). This is Handover Case 2.

In Handover Case 1, the eNB may judge whether handover of the virtualcell is necessary or not, based on the link quality reported by theVC-UE to the eNB. In Handover Case 2, it may be more appropriate for thehandover requirement to be judged by the virtual cell, based on the linkquality between each UE and the virtual cell (and perhaps also each UEand the eNB) as reported to it by each UE, and also on the link qualitybetween the virtual cell and the eNB.

Handover Case 1 may be managed by adaption of the conventional eventtriggered measurement reporting procedure between a base station and aUE so that it applies instead to the eNB and the VC-UE. The VC-UE istriggered to send Measurement Reports to the eNB by an event related tothe measured link quality, and based on the reported link quality, theeNB determines if the VC-UE needs to be handed over. For Handover Case2, however, measurement reporting of the link quality between the UE andthe virtual cell and between the UE and the eNB, which are both measuredby the UE, should be triggered on and off by the link quality betweenthe virtual cell and the eNB. In other words, if the VC-UE moves awayfrom the eNB so that the quality of the link between them drops, the UEcan be triggered to measure and report its own link quality since thismay deteriorate because the VC-UE can no longer sustain the virtualcell.

According to the current specification 3GPP TS 36.331, various eventsare specified for triggering measurement reporting, and can be appliedto a UE and to a UE acting as a virtual cell. However, none of thesetriggers covers the situation according to Handover Case 2. Toaccommodate this, an additional event might be added, defined forexample as “eNB becomes worse than threshold”, i.e. the link qualitybetween the eNB and the VC-UE falls below a pre-set threshold level.This information will not be automatically evident to the UE in thevirtual cell, however, so when this event occurs, the VC-UE canconfigure the UE to begin measurement reporting to the virtual cell. Ifthe link quality then reported from the UE to the VC-UE falls below athreshold, the VC-UE can judge that a handover of the UE to the eNB oranother virtual cell is necessary.

FIG. 14 shows a flow chart of steps in an example procedure for managingmobility in such a way. Starting at step S501, a UE, such as UE5 in FIG.4 , starts operation to provide a virtual cell. During virtual celloperation, the virtual cell performs configured periodic measurements ofthe link quality between itself and the eNB (S502). These measurementscan be reported to the eNB. Passing to decision S503, the virtual celljudges whether or not the quality of this link to the eNB falls below athreshold (which can be set to any convenient value). If the linkquality remains at or above the threshold, the method returns to S503for further judgements at intervals. If the link quality falls below thethreshold in the S503 judgement, the virtual cell configures periodicmeasurement reporting of the UEs belonging to it (S504). In response,each UE begins to report to the virtual cell the link quality of thelink between itself and the virtual cell. It may also report the qualityof the link between itself and the eNB. Passing to decision S505, thevirtual cell judges, for each UE, whether a handover of the UE isnecessary. This can arise if, for example, the link quality between theUE and the virtual cell falls below a threshold, or becomes worse thanthe link quality between the UE and the eNB. If a handover is deemednecessary, the procedure passes to S508 wherein the virtual cellperforms steps required to handover the UE from the virtual cell to theeNB or another virtual cell. Once all of the UEs have been handed overin S508, and because the link between the virtual cell and the eNBjudged in S503 is still considered below threshold, the eNB judges thatthe virtual cell cannot be sustained and initiates either that the UEproviding the virtual cell is handed over to another eNB or that the UEstops its virtual cell operation (S510).

However, in decision S505 if the virtual cell does not find that it isnecessary to handover any UEs, the procedure passes to a furtherdecision at S506, where it is judged whether the link between thevirtual cell and eNB has improved and is now back above the threshold(being the threshold previously used in S503). This may be the reasonfor the UEs not requiring handover, for example—the virtual cell has abetter connection itself so is able to provide better links to the UEs.If the threshold is not exceeded in S506, the method returns to S506 forfurther judging of the need for UE handover. On the other hand, if it isfound at S506 that the link quality between the virtual cell and the eNBis above the threshold, at S507 the virtual cell configures the UEs tostop the periodic reporting of their link qualities (since this nolonger serves any purpose because the virtual cell is again based on agood link and stable operation can be expected). The method then loopsback to S503 for a further check on the virtual cell-to-eNB linkquality.

In this way, the various connections required for sustained qualityoperation of the virtual cell can be monitored in an efficient manner,and appropriate handovers undertaken if the radio connectionsdeteriorate.

Note that the above procedure for mobility management, or modificationsthereof, may be implemented in conjunction with timer-based operation ofthe virtual cell for example as in FIGS. 7 and/or 8 , or separatelytherefrom, according to any performance and operation requirements of anetwork.

The present disclosure relates to RRC connection management between avirtual cell and one or more UEs. With the proposed examples, cellcapacity can be flexibly adapted at hot spot areas in an on-demandmanner. In addition, efficiency of usage of radio resources which may becommonly used by an eNB and a virtual cell can be enhanced.

Various procedures have been described above and the skilled person willunderstand that the teachings provided herein, generally in the contextof existing RRC procedures or of RRC-like procedures, can be equallyapplied to other radio control procedures, states and state transitionsas appropriate.

FIG. 15 illustrates an example method for use in a mobiletelecommunications network or system. The mobile telecommunicationsnetwork or system comprises a base station providing wirelessconnectivity within a base station cell, a mobile node operable toprovide wireless connectivity within a local cell and configured tocommunicate with the base station, and a terminal configured tocommunicate wirelessly with either or both of the base station and themobile node. The method starts, and at S1101 a limited local radioconnection between the terminal and the mobile node is activated.Generally, when this limited local radio connection is activated, theterminal and mobile node are not operable to exchange user data suchthat, while they are connected to each other, they are limited to somesignalling or control communications and are not configured tocommunicate user data such as application data. The method furthercomprises step S1102 in which a timer of fixed duration is activatedwhen or after the limited local radio connection is activated. Themethod then comprises step S1103 wherein, on expiration of the timer, alimited base station radio connection between the terminal and the basestation is activated, and the limited local radio connection between theterminal and the mobile node is terminated. Generally, when the limitedbase station radio connection is activated, the terminal and basestation are not able to exchange user data.

In some examples, the limited connected mode or state that can beactivated by a UE to the VC-UE can be based on the RRC_IDLE or RRCCONNECTED mode with some functionalities de-activated. For example, ifbased on the RRC_IDLE mode, the terminal may be configured to carry out:paging, system information acquisition and UE controlled mobility butnot some other RRC functionalities including a UE specific DRXconfigured by upper layers, performance of neighbouring cellmeasurements and cell (re-)selection based on configuration informationfrom the base station (for example the UE may not receive measurementconfiguration from the base station in cases where the UE alreadyreceives measurement configuration from the local/virtual cell), andperformance of logging of available measurements together with locationand time for logged measurement configured UEs. In the RRC_IDLE mode,the terminal is not able to communicate user data, and this remains thecase in a limited state derived from the RRC_IDLE state.

In another example, if the limited connected state is based on theRRC_CONNECTED state, the following functionalities may be maintained:C-RNTI will be recorded, radio bearer between UE and eNB is retained,network controlled mobility, and acquisition of system information. Onthe other hand, the following functionalities may not be maintained:transfer of unicast data to/from UE, at lower layers, the UE may beconfigured with a UE specific DRX, the UE monitoring control channelsassociated with the shared data channel to determine if data isscheduled for it, the UE providing channel quality and feedbackinformation, and the US performing neighbouring cell measurements andmeasurement reporting based on configuration information from the basestation.

FIG. 16 illustrates an example terminal and an example base stationconfigured to communicate with each other and which may implement one ormore techniques as discussed herein. The terminal 1510 comprises areceiver 1511 and a transmitter 1512 connected to an antenna forcommunicating via a wireless interface. The terminal also comprises acontroller 1513 for controlling at least the receiver and transmitter ofthe terminal 1510. In some examples, the terminal may be configured suchthat the controller, receiver and transmitter may be configured tooperate together to operate as a mobile node to provide a local cell toneighbouring terminals. Likewise, the base station 1520 comprises areceiver 1521 and a transmitter 1522 connected to an antenna forcommunicating via a wireless interface. The base station 1520 alsocomprises a controller 1523 for controlling at least the receiver andtransmitter of the base station 1520. The base station and terminal cancommunicate over the air, via the wireless interface by transmittinguplink signals from the terminal to the base station and downlinksignals from the base station to the terminal. A mobile node inaccordance with the present disclosure may also have the same structureas the terminal and/or base station. Although it is generally expectedthat terminals will be providing local cell functionality, any othersuitable node may provide this functionality.

While FIG. 16 shows a schematic illustration of a terminal and of a basestation, it will be appreciated that while in examples of the presentdisclosure, each terminal includes a transmitter, receiver andcontroller and each base station includes a transmitter, receiver andcontroller so as to allow communication between the terminals and/orbase stations, the terminal and base station may be implemented usingany appropriate technique. For example, the controller may comprise oneor more processor units which are suitably configured/programmed toprovide the desired functionality described herein using conventionalprogramming/configuration techniques for equipment in wirelesstelecommunications systems. For each terminal, the transmitter, receiverand controller are schematically shown in FIG. 16 as separate elementsfor ease of representation. However, it will be appreciated that foreach terminal the functionality of these units can be provided invarious different ways, for example using a single suitably programmedgeneral purpose computer, or suitably configured application-specificintegrated circuit(s)/circuitry, or using a plurality of discretecircuitry/processing elements for providing different elements of thedesired functionality. It will be appreciated the terminals will ingeneral comprise various other elements associated with their operatingfunctionality in accordance with established wireless telecommunicationstechniques (e.g. a power source, possibly a user interface, and soforth).

Generally, in the present disclosure the prefix RRC has been used forstates and connections with the base station and the prefix VC_RRC forstates and connections with the mobile node for the local or virtualcell. However, these have been used in the interest of conciseness only,and unless they are being used specifically in the context RRC only,they are not limited to connections or states of the 3GPP (orequivalent) RRC protocol and are also intended to refer to any otherradio resources control protocol.

Also, the radio resources control protocol, procedure, states orconnections can also be referred to herein as radio, radio control orradio resources protocol, procedure, states or connections,respectively.

As used herein, the term mobile node is used to refer to the nodeproviding the local/virtual cell and the mobile node functionality maybe provided by a terminal, a relay node, a base station, a dedicatednode, or any other suitable node.

As used herein, transmitting information or a message to an element mayinvolve sending one or more messages to the element and may involvesending part of the information separately from the rest of theinformation. The number of “messages” involved may also vary dependingon the layer or granularity considered. For example transmitting amessage may involve using several resource elements in an LTEenvironment such that several signals at a lower layer correspond to asingle message at a higher layer. Also, transmissions from one terminalto another may relate to the transmission of any one or more of userdata, discovery information, control signalling and any other type ofinformation to be transmitted.

Also, whenever an aspect is disclosed in respect of an apparatus orsystem, the teachings are also disclosed for the corresponding method.Likewise, whenever an aspect is disclosed in respect of a method, theteachings are also disclosed for any suitable corresponding apparatus orsystem. Additionally, it is also hereby explicitly disclosed that forany teachings relating to a method or a system where it has not beenclearly specified which element or elements are configured to carry outa function or a step, any suitable element or elements that can carryout the function can be configured to carry out this function or step.For example any one or more of a terminal, a mobile node, a base stationor any other mobile node may be configured accordingly if appropriate,so long as it is technically feasible and not explicitly excluded.

Whenever the expressions “greater than”, or “smaller than” or equivalentare used herein, it is intended that they discloses both alternatives“and equal to” and “and not equal to” unless one alternative isexpressly excluded.

Note that while the present disclosure has been presented largely in thecontext of LTE and/or D2D, its teachings are applicable to but notlimited to LTE or to other 3GPP standards. In particular, even thoughthe terminology used herein is generally the same or similar to that ofthe LTE standards, the teachings are not limited to the present versionof LTE and could apply equally to any appropriate arrangement not basedon LTE and/or compliant with any other future version of an LTE or 3GPPor other standard (e.g. the 5G standards).

Further particular and preferred aspects of the present invention areset out in the accompanying independent and dependent claims. It will beappreciated that features of the dependent claims may be combined withfeatures of the independent claims in combinations other than thoseexplicitly set out in the claims.

Thus, the foregoing discussion discloses and describes merely exemplaryembodiments of the present invention. As will be understood by thoseskilled in the art, the present invention may be embodied in otherspecific forms without departing from the spirit or essentialcharacteristics thereof. Accordingly, the disclosure of the presentinvention is intended to be illustrative, but not limiting of the scopeof the invention, as well as other claims. The disclosure, including anyreadily discernible variants of the teachings herein, define, in part,the scope of the foregoing claim terminology such that no inventivesubject matter is dedicated to the public. Respective features of thepresent disclosure are defined by the following numbered clauses:

Clause 1. A method for use in a mobile telecommunications network, themobile telecommunications network comprising a base station providingwireless connectivity within a base station cell, a mobile nodeproviding wireless connectivity within a local cell and configured tocommunicate wirelessly with the base station, and a terminal configuredto communicate wirelessly with the base station and configured tocommunicate wirelessly with the mobile node; the method comprising:

activating a limited local radio connection between the terminal and themobile node;

starting a first timer of fixed duration when or after the limited localradio connection is activated; and

when the first timer has expired, activating a limited base stationradio connection between the terminal and the base station andterminating the limited local radio connection between the terminal andthe mobile node.

Clause 2. The method of clause 1 in which the activating the limitedlocal radio connection between the terminal and the mobile node isperformed by transitioning from a full local radio connection betweenthe terminal and the mobile node to the limited local radio connectionwhen a transfer of data between the terminal and the mobile node hasbeen completed.

Clause 3. The method of clause 1 or 2, and further comprising, if thereis a need for a transfer of data between the terminal and the mobilenode before the first timer has expired, transitioning from the limitedlocal radio connection to a full local radio connection between theterminal and the mobile node; and deactivating the first timer.

Clause 4. The method of any one of clauses 1-3, and further comprising:

monitoring for a requirement to transfer data between the terminal andthe mobile node after the first timer has started;

if the requirement occurs, transitioning from the limited local radioconnection to a full local radio connection between the terminal and themobile node; and

deactivating the first timer.

Clause 5. The method of any one of clauses 1-4, in which the first timerbelongs to the terminal.

Clause 6. The method of clause 5, in which the fixed duration of thefirst timer is set during manufacture or maintenance of the terminal.

Clause 7. The method of clause 5, in which the fixed duration of thefirst timer is determined by the mobile node and provided to theterminal by the mobile node.

Clause 8. The method of clause 5, in which the fixed duration of thefirst timer is determined with reference to an extent of coverage of thelocal cell and/or a buffer status of the mobile node or the basestation.

Clause 9. The method of any one of clauses 1-8, further comprising

activating the mobile node to provide wireless connectivity to theterminal within the local cell;

starting a second timer of fixed duration when or after the mobile nodeis activated;

when the second timer has expired, terminating activity of the mobilenode that provides the wireless connectivity to the terminal.

Clause 10. The method of clause 9, in which activating the mobile nodeincludes transitioning from a limited base station radio connectionbetween the mobile node and the base station to a full base stationradio connection between the mobile node and the base station.

Clause 11. The method of clause 9 or clause 10, and further comprising:

monitoring for data transmission and/or reception between the mobilenode and the terminal after the second timer has started; and

if said data transmission and/or reception occurs, restarting the secondtimer.

Clause 12. The method of any one of clauses 9-11, in which the fixedduration of the second timer is equal to or longer than the fixedduration of the first timer.

Clause 13. The method of any one of clauses 9-12, in which the secondtimer belongs to the mobile node.

Clause 14. The method of any one of clauses 9-13, in which the fixedduration of the second timer is set during manufacture or maintenance ofthe mobile node.

Clause 15. The method of any one of clauses 9-13, in which the fixedduration of the second timer is determined by the mobile node or thebase station.

Clause 16. The method of any one of clauses 9-13, in which the fixedduration of the second timer is determined with reference to an extendof coverage of the local cell and/or a buffer status of the mobile nodeor the base station.

Clause 17. The method of any one of clauses 1-16, further comprising:

before or after starting the first timer, monitoring the quality of afull base station radio connection between the mobile node and the basestation; and

if the quality falls below a first threshold, terminating provision ofwireless connectivity within the local cell by the mobile node.

Clause 18. The method of clause 17, further comprising, beforeterminating provision of wireless connectivity with the local cell,triggering the terminal to periodically report to the mobile node thequality of a limited or full local radio connection between the terminaland the mobile node.

Clause 19. The method of clause 18, further comprising:

monitoring the reported quality of the radio connection between theterminal and the mobile node; and

if the reported quality falls below a second threshold, performing ahandover of the terminal from the local cell to the base station cell ora different local cell.

Clause 20. The method of clause 19, in which, if the reported qualityremains at or above the second threshold, checking the quality of thefull base station radio connection between the mobile node and the basestation and if it has risen above the first threshold, stopping theterminal from periodically reporting to the mobile node the quality ofthe radio connection between the terminal and the mobile node.

Clause 21. A mobile telecommunications network, the mobiletelecommunications network comprising a base station providing wirelessconnectivity within a base station cell, a mobile node providingwireless connectivity within a local cell and configured to communicatewirelessly with the base station, and a terminal configured tocommunicate wirelessly with the base station and configured tocommunicate wirelessly with the mobile node, wherein the mobiletelecommunications network is configured to:

activate a limited local radio connection between the terminal and themobile node;

start a first timer of fixed duration when or after the limited localradio connection is activated; and

when the first timer has expired, activate a limited base station radioconnection between the terminal and the base station and terminate thelimited local radio connection between the terminal and the mobile node.

Clause 22. A mobile telecommunications network, the mobiletelecommunications network comprising a base station providing wirelessconnectivity within a base station cell, a mobile node providingwireless connectivity within a local cell and configured to communicatewirelessly with the base station, and a terminal configured tocommunicate wirelessly with the base station and configured tocommunicate wirelessly with the mobile node, wherein the mobiletelecommunications network is configured to carry out the method of anyone of clauses 1-20.

Clause 23. A method of operating a terminal for use in a mobiletelecommunications network comprising a base station providing wirelessconnectivity within a base station cell, and a mobile node providingwireless connectivity within a local cell and configured to communicatewirelessly with the base station, wherein the terminal comprises atransmitter, a receiver and a controller and is configured tocommunicate wirelessly with the base station and to communicatewirelessly with the mobile node, the method comprising:

the terminal activating a limited local radio connection between theterminal and the mobile node; the terminal starting a first timer offixed duration when or after the limited local radio connection isactivated; and

when the first timer has expired, the terminal activating a limited basestation radio connection between the terminal and the base station andterminating the limited local radio connection between the terminal andthe mobile node.

Clause 24. The method of clause 23, in which the terminal activating thelimited local radio connection between the terminal and the mobile nodeis performed by the terminal transitioning from a full local radioconnection between the terminal and the mobile node to the limited localradio connection when a transfer of data between the terminal and themobile node has been completed.

Clause 25. The method of clause 23 or clause 24, and further comprising:

the terminal monitoring for a requirement to transfer data between theterminal and the mobile data after the first timer has started;

if the requirement occurs, the terminal transitioning from the limitedlocal radio connection to a full local radio connection between theterminal and the mobile node;

the terminal deactivating the first timer.

Clause 26. The method of any one of clauses 23-25, in which the firsttimer belongs to the terminal.

Clause 27. The method of any one of clauses 23-26, further comprisingsetting the fixed duration of the first timer during manufacture ormaintenance of the terminal.

Clause 28. The method of any one of clauses 23-26, further comprisingthe terminal receiving the fixed duration of the first timer from themobile node.

Clause 29. The method of any one of clauses 23-28, further comprising:

the terminal periodically reporting to the mobile node the quality of alimited or full local radio connection between the terminal and themobile node, in response to a trigger from the mobile node following afall below a first threshold of the quality of a full base station radioconnection between the mobile node and the base station.

Clause 30. The method of clause 29, further comprising:

the terminal participating in a handover from the local cell to the basestation or a different local cell if the reported quality of radioconnection between the terminal and the mobile node falls below a secondthreshold.

Clause 31. The method of clause 30, further comprising:

the terminal ceasing to periodically report to the mobile node thequality of the radio connection between the terminal and the mobile nodeif the quality of the full base station radio connection between themobile node and the base station rises above the first threshold.

Clause 32. A terminal for use in a mobile telecommunications networkcomprising a base station providing wireless connectivity within a basestation cell, and a mobile node providing wireless connectivity within alocal cell and configured to communicate wirelessly with the basestation, wherein the terminal comprises a transmitter, a receiver and acontroller and is configured to communicate wirelessly with the basestation and to communicate wirelessly with the mobile node, wherein theterminal is further configured to:

activate a limited local radio connection between the terminal and themobile node;

start a first timer of fixed duration when or after the limited localradio connection is activated; and

when the first timer has expired, activate a limited base station radioconnection between the terminal and the base station and terminating thelimited local radio connection between the terminal and the mobile node.

Clause 33. Circuitry for a terminal for use in a mobiletelecommunications network comprising a base station providing wirelessconnectivity within a base station cell, and a mobile node providingwireless connectivity within a local cell and configured to communicatewirelessly with the base station; wherein the circuitry comprises acontroller element and a transceiver element configured to operatetogether to:

activate a limited local radio connection between the terminal and themobile node;

start a first timer of fixed duration when or after the limited localradio connection is activated; and

when the first timer has expired, activate a limited base station radioconnection between the terminal and the base station and terminating thelimited local radio connection between the terminal and the mobile node.

Clause 34. A method of operating a mobile node in a mobiletelecommunications network comprising a base station providing wirelessconnectivity within a base station cell, the mobile node which isconfigured to provide wireless connectivity within a local cell andconfigured to communicate wirelessly with the base station, and aterminal configured to communicate wirelessly with the base station andconfigured to communicate wirelessly with the mobile node, the methodcomprising the mobile node:

activating wireless connectivity to the terminal within the local cell;

starting a timer of fixed duration when or after wireless connectivityis activated; and

when the timer has expired, terminating the wireless connectivity to theterminal within the local cell.

Clause 35. The method of clause 34, in which the mobile node activatingthe wireless connectivity to the terminal within the local cell includesthe mobile node transitioning from a limited base station radioconnection between the mobile node and the base station to a full basestation radio connection between the mobile node and the base station.

Clause 36. The method of clause 34 or clause 35, further comprising themobile node:

monitoring for data transmission and/or reception between the mobilenode and the terminal after the timer has started; and

if said data transmission and/or reception occurs, restarting the timer.

Clause 37. The method of any one of clauses 34-36, in which the fixedduration of the timer is equal to or longer than a fixed duration of afirst timer belonging to the terminal and able to be activated when orafter a limited local radio connection between the terminal and themobile node is activated.

Clause 38. The method of any one of clauses 34-37, in which the timerbelongs to the mobile node.

Clause 39. The method of clause 38, further comprising setting the fixedduration of the timer during manufacture or maintenance of the mobilenode.

Clause 40. The method of clause 38, further comprising the mobile nodedetermining the fixed duration of the timer with reference to an extentof coverage of the local cell and/or a buffer status of the mobile nodeor the base station.

Clause 41. The method of any one of clauses 34-40, further comprisingthe mobile node:

monitoring the quality of a full base station radio connection betweenthe mobile node and the base station; and

if the quality falls below a first threshold, terminating provision ofwireless connectivity within the local cell.

Clause 42. The method of clause 41, further comprising the mobile node:

before terminating provision of wireless connectivity with the localcell, triggering the terminal to periodically report to the mobile nodethe quality of a limited or full local radio connection between theterminal and the mobile node.

Clause 43. The method of clause 42, further comprising the mobile node:

monitoring the reported quality of the radio connection between theterminal and the mobile node; and

if the reported quality falls below a second threshold, initiating ahandover of the terminal from the local cell to the base station cell ora different local cell.

Clause 44. The method of clause 43, in which, if the reported qualityremains at or above the second threshold, the mobile node checks thequality of the full base station radio connection between the mobilenode and the base station and if it has risen above the first threshold,stops the terminal from periodically reporting to the mobile node thequality of the radio connection between the terminal and the mobilenode.

Clause 45. A mobile node for use in a mobile telecommunications networkcomprising a base station providing wireless connectivity within a basestation cell, the mobile node which is configured to provide wirelessconnectivity within a local cell and configured to communicatewirelessly with the base station, and a terminal configured tocommunicate wirelessly with the base station and configured tocommunication wirelessly with the mobile node, the mobile nodecomprising a transmitter, a receiver and a controller, and furtherconfigured to:

activate wireless connectivity to the terminal within the local cell;

start a timer of fixed duration when or after wireless connectivity isactivated; and

when the timer has expired, terminate the wireless connectivity to theterminal within the local cell.

Clause 46. Circuitry for a mobile node for use in a mobiletelecommunications network comprising a base station providing wirelessconnectivity within a base station cell, the mobile node, and a terminalconfigured to communicate wirelessly with the base station andconfigured to communicate wirelessly with the mobile node, circuitrycomprising a controller element and a transceiver element configured to:

operate together to provide wireless connectivity within a local celland to communicate with the base station;

activate wireless connectivity to the terminal within the local cell;

start a timer of fixed duration when or after the wireless connectivityto the terminal within the local cell is activated; and

when the timer has expired, terminate the wireless connectivity to theterminal within the local cell.

Clause 47. A method of operating a base station in a mobiletelecommunications network, the base station comprising a transmitter, areceiver and a controller and being configured to provide wirelessconnectivity within a base station cell, the mobile telecommunicationsnetwork comprising the base station, a mobile node providing wirelessconnectivity within a local cell and configured to communicatewirelessly with the base station, and a terminal configured tocommunicate wirelessly with the base station and configured tocommunicate wirelessly with the mobile node, the base station furtherconfigured to:

activate a limited base station radio connection between the terminaland the base station when a timer of fixed duration has expired afterhaving been started in response to activation of a limited local radioconnection between the terminal and the mobile node.

Clause 48. A base station for use in a mobile telecommunications networkcomprising the base station, a mobile node providing wirelessconnectivity within a local cell and configured to communicatewirelessly with the base station, and a terminal configured tocommunicate wirelessly with the base station and configured tocommunicate wirelessly with the mobile node, the base station comprisinga transmitter, a receiver and a controller and being configured to:

provide wireless connectivity within a base station cell; and

activate a limited base station radio connection between the terminaland the base station when a timer of fixed duration has expired afterhaving been started in response to activation of a limited local radioconnection between the terminal and the mobile node.

Clause 49. Circuitry for a base station for use in a mobiletelecommunications network comprising the base station, a mobile nodeproviding wireless connectivity within a local cell and configured tocommunicate wirelessly with the base station, and a terminal configuredto communicate wirelessly with the base station and configured tocommunicate wirelessly with the mobile node, the circuitry comprising acontroller element and a transceiver element configured to:

provide wireless connectivity within a base station cell; and

activate a limited base station radio connection between the terminaland the base station when a timer of fixed duration has expired afterhaving been started in response to activation of a limited local radioconnection between the terminal and the mobile node.

Clause 50. Computer software which, when executed by a computer causesthe computer to perform the methods of any one of clauses 1-20, 23-31,34-44 or 47.

Clause 51. A storage medium which store computer software according toclause 50.

REFERENCES

-   [1] Holma H. and Toskala A., “LTE for UMTS OFDMA and SC-FDMA based    radio access”, John Wiley and Sons, 2009-   [2] TS 36.331, v12.7.0, 2015-09, Technical Specification Document    for “Evolved Universal Terrestrial Radio Access (E-UTRA); Radio    Resource Control (RRC); Protocol specification”-   [3] 3GPP TS 36.300: 4.7 Support for relaying

What is claimed is:
 1. A mobile node for use in a mobiletelecommunications network comprising a base station providing wirelessconnectivity within a base station cell, the mobile node which isconfigured to provide wireless connectivity within a local cell andconfigured to communicate wirelessly with the base station, and aterminal configured to communicate wirelessly with the base station andconfigured to communication wirelessly with the mobile node, the mobilenode comprising circuitry configured to: activate wireless connectivityto the terminal within the local cell, wherein the local cellcorresponding to the mobile node is established on-demand in response toa spatial concentration of a plurality of terminals, the mobile nodebeing selected from the plurality of terminals in the spatialconcentration based on the mobile node having an idle state; start atimer of fixed duration when or after wireless connectivity isactivated; and in response to the timer expiring, terminate the wirelessconnectivity to the terminal within the local cell.
 2. The mobile nodeof claim 1, wherein the circuitry for activating the wirelessconnectivity to the terminal within the local cell is further configuredto transition the mobile node from a limited base station radioconnection between the mobile node and the base station to a full basestation radio connection between the mobile node and the base station.3. The mobile node of claim 1, wherein the circuitry is furtherconfigured to monitor for data transmission and/or reception between themobile node and the terminal after the timer has started, and inresponse to said data transmission and/or reception occurring, restartthe timer.
 4. The mobile node of claim 1, wherein the fixed duration ofthe timer is equal to or longer than a fixed duration of a first timerbelonging to the terminal and able to be activated when or after alimited local radio connection between the terminal and the mobile nodeis activated.
 5. The mobile node of claim 1, wherein the timer belongsto the mobile node.
 6. The mobile node of claim 5, wherein the circuitryis further configured to set the fixed duration of the timer duringmanufacture or maintenance of the mobile node.
 7. The mobile node ofclaim 5, wherein the circuitry is further configured to determine thefixed duration of the timer with reference to an extent of coverage ofthe local cell and/or a buffer status of the mobile node or the basestation.
 8. The mobile node of claim 1, wherein the circuitry is furtherconfigured to monitor the quality of a full base station radioconnection between the mobile node and the base station, and in responseto the quality falling below a first threshold, terminate provision ofwireless connectivity within the local cell.
 9. The mobile node of claim8, wherein the circuitry is further configured to before terminatingprovision of wireless connectivity with the local cell, trigger theterminal to periodically report to the mobile node the quality of alimited or full local radio connection between the terminal and themobile node.
 10. The mobile node of claim 9, wherein the circuitry isfurther configured to monitor the reported quality of the radioconnection between the terminal and the mobile node, and in response tothe reported quality falling below a second threshold, initiate ahandover of the terminal from the local cell to the base station cell ora different local cell.
 11. The mobile node of claim 10, wherein inresponse to the reported quality remaining at or above the secondthreshold, the circuitry is further configured to check the quality ofthe full base station radio connection between the mobile node and thebase station and in response to the quality having risen above the firstthreshold, stop the terminal from periodically reporting to the mobilenode the quality of the radio connection between the terminal and themobile node.
 12. Circuitry for a mobile node for use in a mobiletelecommunications network comprising a base station providing wirelessconnectivity within a base station cell, the mobile node, and a terminalconfigured to communicate wirelessly with the base station andconfigured to communicate wirelessly with the mobile node, wherein thecircuitry is configured to: provide wireless connectivity within a localcell and to communicate with the base station; activate wirelessconnectivity to the terminal within the local cell, wherein the localcell corresponding to the mobile node is established on-demand inresponse to a spatial concentration of a plurality of terminals, themobile node being selected from the plurality of terminals in thespatial concentration based on the mobile node having an idle state;start a timer of fixed duration when or after the wireless connectivityto the terminal within the local cell is activated; and in response tothe timer expiring, terminate the wireless connectivity to the terminalwithin the local cell.
 13. The circuitry for the mobile node of claim12, wherein the circuitry for activating the wireless connectivity tothe terminal within the local cell is further configured to transitionthe mobile node from a limited base station radio connection between themobile node and the base station to a full base station radio connectionbetween the mobile node and the base station.
 14. The circuitry for themobile node of claim 12, wherein the circuitry is further configured tomonitor for data transmission and/or reception between the mobile nodeand the terminal after the timer has started, and in response to saiddata transmission and/or reception occurring, restart the timer.
 15. Thecircuitry for the mobile node of claim 12, wherein the fixed duration ofthe timer is equal to or longer than a fixed duration of a first timerbelonging to the terminal and able to be activated when or after alimited local radio connection between the terminal and the mobile nodeis activated.
 16. The circuitry for the mobile node of claim 12, whereinthe timer belongs to the mobile node, wherein the circuitry is furtherconfigured to set the fixed duration of the timer during manufacture ormaintenance of the mobile node, and determine the fixed duration of thetimer with reference to an extent of coverage of the local cell and/or abuffer status of the mobile node or the base station.
 17. The circuitryfor the mobile node of claim 12, wherein the circuitry is furtherconfigured to monitor the quality of a full base station radioconnection between the mobile node and the base station, and in responseto the quality falling below a first threshold, terminate provision ofwireless connectivity within the local cell.
 18. The circuitry for themobile node of claim 17, wherein the circuitry is further configured tobefore terminating provision of wireless connectivity with the localcell, trigger the terminal to periodically report to the mobile node thequality of a limited or full local radio connection between the terminaland the mobile node.
 19. The circuitry for the mobile node of claim 18,wherein the circuitry is further configured to monitor the reportedquality of the radio connection between the terminal and the mobilenode, and in response to the reported quality falling below a secondthreshold, initiate a handover of the terminal from the local cell tothe base station cell or a different local cell, wherein in response tothe reported quality remaining at or above the second threshold, thecircuitry is further configured to check the quality of the full basestation radio connection between the mobile node and the base stationand in response to the quality having risen above the first threshold,stop the terminal from periodically reporting to the mobile node thequality of the radio connection between the terminal and the mobilenode.
 20. A method of operating a base station in a mobiletelecommunications network, the base station comprising a transmitter, areceiver and a controller and being configured to provide wirelessconnectivity within a base station cell, the mobile telecommunicationsnetwork comprising the base station, a mobile node providing wirelessconnectivity within a local cell and configured to communicatewirelessly with the base station, and a terminal configured tocommunicate wirelessly with the base station and configured tocommunicate wirelessly with the mobile node, the method comprising:activating a limited base station radio connection between the terminaland the base station when a timer of fixed duration has expired afterhaving been started in response to activation of a limited local radioconnection between the terminal and the mobile node, wherein the localcell corresponding to the mobile node is established on-demand inresponse to a spatial concentration of a plurality of terminals, themobile node being selected from the plurality of terminals in thespatial concentration based on the mobile node having an idle state.